Twenty-plus years of lively development in hip joint prosthesis design have not produced a fully satisfactory solution to the problem of stem loosening; it still is a major long-term complication. Current trends towards bone integration are addressing only some, perhaps minor problems of prosthesis-bone interaction.
A femoral component for an artificial hip joint is known from the German Offenlegungsschrift no. 31 13 898 in which the stem is formed by several anchoring rods which together with a collar are made from one solid casting. The rods are pressed against the inside of the bone by plugs, thereby producing a locking effect. A fixation system of this kind is not only difficult and time-consuming to insert but produces still an uncontrolled, uneven load transfer from the stemmed component of the joint endo-prosthesis to the bone with high load concentrations at the end of the stem.